[lldb] Make SBSection::GetSectionData call Section::GetSectionData.

[jgorbe]

Summary

SBSection::GetSectionData and Section::GetSectionData are
implemented differently, and the SBSection method doesn't handle
compressed sections correctly.

[dblaikie]

lldb/source/API/SBSection.cpp

187–189

Probably either use std::move when passing result_data_sp to SetOpaque, or roll the expressions together (to avoid an unnecessary copy of a ref counted smart pointer, that would cause extra increment/decrement of the ref count)

[jgorbe]

Addressing review comment.

[jgorbe]

lldb/source/API/SBSection.cpp

187–189

Done, inlined result_data_sp into the SetOpaque call. Thanks!

[omjavaid]

LLDB windows buildbots were broken by the TestSectionAPI.py test. I dont
have full context of the commit to fix it. Reverting it temporarily.

https://lab.llvm.org/buildbot/#/builders/83/builds/28617
https://lab.llvm.org/buildbot/#/builders/219/builds/180

[labath]

I'm pretty sure that's because that bot builds without zlib support. You'll need to add something like @skipIfXmlSupportMissing to this test (I think we don't have a decorator for zlib now, so you'll probably need to add one).

While you're at it, you might as well slap @no_debug_info_test on it.

[labath]

I'm sorry Omair, my comment was meant for Jorge, not you. @skipIfXml is not the right decorator here, although it will probably kinda fix the failure (because the bot does not have xml support either). I *think* the compressed section support is controlled by presence of zlib.

Since the bot is not immediately broken, I think we can leave bde5d31 in to avoid the churn. Jorge, could you replace the xml thingy with a more appropriate decorator?

lldb/source/API/SBSection.cpp

 }
 
 SBData SBSection::GetSectionData(uint64_t offset, uint64_t size) {
   LLDB_INSTRUMENT_VA(this, offset, size);
 
   SBData sb_data;
   SectionSP section_sp(GetSP());
   if (section_sp) {
-    const uint64_t sect_file_size = section_sp->GetFileSize();
-    if (sect_file_size > 0) {
-      ModuleSP module_sp(section_sp->GetModule());
-      if (module_sp) {
-        ObjectFile *objfile = module_sp->GetObjectFile();
-        if (objfile) {
-          const uint64_t sect_file_offset =
-              objfile->GetFileOffset() + section_sp->GetFileOffset();
-          const uint64_t file_offset = sect_file_offset + offset;
-          uint64_t file_size = size;
-          if (file_size == UINT64_MAX) {
-            file_size = section_sp->GetByteSize();
-            if (file_size > offset)
-              file_size -= offset;
-            else
-              file_size = 0;
-          }
-          auto data_buffer_sp = FileSystem::Instance().CreateDataBuffer(
-              objfile->GetFileSpec().GetPath(), file_size, file_offset);
-          if (data_buffer_sp && data_buffer_sp->GetByteSize() > 0) {
-            DataExtractorSP data_extractor_sp(
-                new DataExtractor(data_buffer_sp, objfile->GetByteOrder(),
-                                  objfile->GetAddressByteSize()));
-
-            sb_data.SetOpaque(data_extractor_sp);
-          }
-        }
-      }
-    }
+    DataExtractor section_data;
+    section_sp->GetSectionData(section_data);
+    sb_data.SetOpaque(
+        std::make_shared<DataExtractor>(section_data, offset, size));
   }
   return sb_data;
 }
 
 SectionType SBSection::GetSectionType() {
   LLDB_INSTRUMENT_VA(this);
 
   SectionSP section_sp(GetSP());
   if (section_sp.get())

lldb/test/API/python_api/section/TestSectionAPI.py

def test_get_alignment(self):
         self.yaml2obj("aligned.yaml", exe)
         target = self.dbg.CreateTarget(exe)
         self.assertTrue(target, VALID_TARGET)
 
         # exe contains a single section aligned to 0x1000
         section = target.modules[0].sections[0]
         self.assertEqual(section.GetAlignment(), 0x1000)
         self.assertEqual(section.alignment, 0x1000)
+
+    def test_compressed_section_data(self):
+        exe = self.getBuildArtifact("compressed-sections.out")
+        self.yaml2obj("compressed-sections.yaml", exe)
+        target = self.dbg.CreateTarget(exe)
+        self.assertTrue(target, VALID_TARGET)
+
+        # exe contains a single section with SHF_COMPRESSED. Check that
+        # GetSectionData returns the uncompressed data and not the raw contents
+        # of the section.
+        section = target.modules[0].sections[0]
+        section_data = section.GetSectionData().uint8s
+        self.assertEqual(section_data,
+                         [0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80, 0x90])
+

lldb/test/API/python_api/section/compressed-sections.yaml

+--- !ELF
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_386
+Sections:
+  - Name:            .compressed
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_COMPRESSED ]
+    Content:         010000000800000001000000789c5330700848286898000009c802c1